Originally Posted by imagic
I don't know if this helps, but after this whole thread turned around I started messing with my Crown XTi-1000 and some subs. I can't measure voltages and watts and all that (yet), so I have to go with how the system reacted to different loads and impedance when playing the same sine waves and/or test tracks. In a nutshell, the lower the impedance, the cleaner the power... but 'failure' occurs through hard clipping which sounds distinctly mechanical (clanking in my case)... that's the clipping that destroys speakers in nanosecond. The higher the impedance, the softer the clipping - at 8ohms it's been replaced by THD and dynamic compression which gives the (false) impression of more power because you can still turn the volume up and it seems to provide more power even than 2 ohms but of course it's just getting dirtier... very fast. I have four DVC drivers, two are 2 ohm VC and two are 4 ohm VC, so I wired the whole thing to run with a combined impedance of 3 ohms per channel, and it is by far the cleanest and most powerful configuration I've had... good resistance to clipping, no distortion before that clipping manifests... and with a modded fan the amp is staying cool even on tougher bass sequences. I do need to step up my amp game, in fact I'm sure I need to do that before I buy any more drivers at all. Something with at least double the power of the XTi-1000 (like the Xti-4002). Gotta admit, I'm partial to Crown I cannot overstate how much abuse this XTi-1000 has taken over the past 5 years. I take its reliability for granted.
I wonder if you could audition an XTi-6002 and see how it stacks up to the clone? One thing I know for sure, the Kicker Solo-X 18"
is no longer something I am looking at, I can't afford to amp that driver properly so why bother. Instead I'm going to work with multiple Polk MM15DVC
because they are very efficient and inexpensive and the math really works in their favor using amps I can afford... plus I've used one long enough that I feel very comfortable with it - good SQ, very resilient. It's certainly the opposite of those mega-woofers but it is very good in its own way. As appealing as 'crazy-ass 18" solid-stone woofer' is to me, I finally ran into a WAF wall on that one.
Haaha… So AVS isn’t going to see its first bolder build? Hey, WAF is a part of life… We all face it at some point. Especially those who like to push the limits. Your current setup looks good man! For the price of one ultra you could get a lot of decent options in multiples.
Ok, I have a few questions for you regarding your post above… You indicate that you have four drivers that you are pushing with your XTi-1000. Two are 2ohm DVC and the other two are 4ohm DVC. That’s how I interpret your post, is that correct?
Are all four subs the same drivers (power rating, etc…) but with two different VC impedances?
The XTi-1000 is a single channel amp… I’m not sure how you have wired the VC’s of your subs, but if you aren’t already aware, they are seeing different power from the amp. While you calculated that your amp sees a “3 ohm” load, your 2ohm DVC subs are getting more (or less depending on how you have the VC wired) power than your 4ohm DVC subs. So you are physically pushing one type (pair) of subs harder....
Make sense? I don’t recommend mixing multiple VC impedances on the same channel. Now, if you had a 4ohm SVC and a 2ohm DVC that you could series to 4ohm, then each sub would see the same power and be pushed at the same level. I personally wouldn’t go that route unless I absolutely had too for some weird reason?
Just keep that in mind my friend. Don’t go blowing $hit up… Or if you do, make sure it’s well documented with a video.